public byte[] HandleRequest(byte[] requestBytes)
        {
            object request = DiffPrivRequest.ParseRequest(requestBytes);

            if (request is Common.GetQuoteRequest)
            {
                GetQuoteResponse getQuoteResponse = new GetQuoteResponse(0, key_pair);
                return(getQuoteResponse.Encode());
            }
            if (request is InitializeDBRequest)
            {
                InitializeDBRequest r = (InitializeDBRequest)request;
                if (rows_received != 0)
                {
                    Console.Error.WriteLine("Received request to initialize DB after receiving rows");
                    return(DiffPrivSrvResponse.EncodeInitializeDBResponse(18));
                }

                if (r.budget_num < r.budget_den)
                {
                    Console.Error.WriteLine("Received request to initialize DB with budget < 1");
                    return(DiffPrivSrvResponse.EncodeInitializeDBResponse(16));
                }

                budget = new BigRational(r.budget_num, r.budget_den);
                rows.Clear();
                return(DiffPrivSrvResponse.EncodeInitializeDBResponse(0));
            }
            if (request is AddRowRequest)
            {
                byte[] ciphertext = ((AddRowRequest)request).ciphertext;
                byte[] plaintext;
                try
                {
                    plaintext = key_pair.Decrypt(ciphertext, false);
                }
                catch
                {
                    Console.Error.WriteLine("Received undecryptable add-row request");
                    return(DiffPrivSrvResponse.EncodeAddRowResponse());
                }

                HandleAddRowRequest(plaintext);
                return(DiffPrivSrvResponse.EncodeAddRowResponse());
            }
            if (request is QueryRequest)
            {
                QueryRequest r = (QueryRequest)request;
                return(HandleQueryRequest(r));
            }
            return(InvalidResponse.Encode());
        }
        public byte[] HandleQueryRequest(QueryRequest request)
        {
            if (request.row_min > request.row_max)
            {
                Console.Error.WriteLine("Row value range empty");
                return(DiffPrivSrvResponse.EncodeQueryResponse(1, 0));
            }
            if (request.answer_min > request.answer_max)
            {
                Console.Error.WriteLine("Answer range empty");
                return(DiffPrivSrvResponse.EncodeQueryResponse(2, 0));
            }
            if (request.answer_units <= 0)
            {
                Console.Error.WriteLine("Answer units not positive");
                return(DiffPrivSrvResponse.EncodeQueryResponse(3, 0));
            }
            if (request.alpha_num <= request.alpha_den)
            {
                Console.Error.WriteLine("Alpha not greater than 1");
                return(DiffPrivSrvResponse.EncodeQueryResponse(6, 0));
            }
            if (request.beta_num <= request.beta_den)
            {
                Console.Error.WriteLine("Beta not greater than 1");
                return(DiffPrivSrvResponse.EncodeQueryResponse(13, 0));
            }

            UInt32[]      program_words = CommonRoutines.BEByteSeqToWordSeq(request.program_encoding);
            MapperProgram program       = new MapperProgram(program_words);

            if (!program.IsValid())
            {
                Console.Error.WriteLine("Invalid program provided for query");
                return(DiffPrivSrvResponse.EncodeQueryResponse(4, 0));
            }

            if (request.answer_units >= 0x80000000)
            {
                Console.Error.WriteLine("Answer granularity too high");
                return(DiffPrivSrvResponse.EncodeQueryResponse(17, 0));
            }

            BigRational alpha = new BigRational(request.alpha_num, request.alpha_den);
            BigRational beta  = new BigRational(request.beta_num, request.beta_den);
            UInt32      delta = DivideRoundingUp(request.row_max - request.row_min, request.answer_units);
            UInt32      B     = request.answer_max - request.answer_min;

            if (B <= 0)
            {
                Console.Error.WriteLine("Answer range empty");
                return(DiffPrivSrvResponse.EncodeQueryResponse(5, 0));
            }
            if (alpha <= new BigRational(1))
            {
                return(DiffPrivSrvResponse.EncodeQueryResponse(6, 0));
            }
            BigRational alpha_to_delta = BigRational.Power(alpha, delta);

            if (beta <= alpha_to_delta)
            {
                Console.Error.WriteLine("Beta not greater than alpha to the power of delta");
                return(DiffPrivSrvResponse.EncodeQueryResponse(7, 0));
            }

            if (beta > budget)
            {
                Console.Error.WriteLine("Not enough budget for request");
                return(DiffPrivSrvResponse.EncodeQueryResponse(11, 0));
            }

            BigRational one = new BigRational(1);
            BigRational two = new BigRational(2);
            BigRational min_alpha_minus_1_and_2 = alpha - one;

            if (min_alpha_minus_1_and_2 > two)
            {
                min_alpha_minus_1_and_2 = two;
            }
            BigRational noiseEntropyPart1 = (alpha + one) * (beta + one) / ((beta - alpha_to_delta) * min_alpha_minus_1_and_2);

            UInt32 r1;

            if (!FindHigherPowerOfTwo(noiseEntropyPart1, out r1) || r1 >= 0xFFFFFFE0)
            {
                Console.Error.WriteLine("Requires too many bits of randomness due to noise entropy part 1");
                return(DiffPrivSrvResponse.EncodeQueryResponse(8, 0));
            }

            UInt32 log_alpha;

            if (!FindHigherPowerOfTwo(alpha, out log_alpha) || log_alpha > 0xFFFFFFFFUL / B)
            {
                Console.Error.WriteLine("Requires too many bits of randomness due to alpha");
                return(DiffPrivSrvResponse.EncodeQueryResponse(8, 0));
            }

            UInt32 r2 = log_alpha * (B - 1);

            if (r2 >= 0xFFFFFFC8 - r1)
            {
                Console.Error.WriteLine("Requires too many bits of randomness due to r2");
                return(DiffPrivSrvResponse.EncodeQueryResponse(8, 0));
            }

            UInt32 r = RoundUpToMultiple(r1 + r2 + 7, 8);
            UInt32 num_randoms_needed = RoundUpToMultiple(r / 8, 4) + 1;

            bool negate_noise = (rng.Next() % 2 == 0);

            byte[] randoms = new byte[num_randoms_needed];
            rng.NextBytes(randoms);
            randoms[num_randoms_needed - 1] = 0;
            BigInteger U = new BigInteger(randoms);

            BigRational one_half    = new BigRational(1, 2);
            BigRational numerator   = new BigRational(U) + one_half;
            BigRational denominator = BigRational.Power(two, (num_randoms_needed - 1) * 8);
            BigRational u           = numerator / denominator;

            BigRational threshold      = (two * alpha) / (u * (alpha + one));
            UInt32      absolute_noise = FindHighestPowerLeThreshold(alpha, threshold, B);

            UInt32 answer        = ComputeSum(program, request.row_min, request.row_max, request.answer_units, request.answer_min, request.answer_max);
            UInt32 noised_answer = AddNoise(answer, absolute_noise, negate_noise);
            UInt32 response      = ClipWord32(noised_answer, request.answer_min, request.answer_max);

            budget = budget / beta;
            return(DiffPrivSrvResponse.EncodeQueryResponse(0, response));
        }